Position indicating device for dental x-ray machines

ABSTRACT

A position indicating device for dental X-ray machines comprising a lead lined tubular member having an X-ray receiving end and an X-ray emitting end, with the tubular member at its Xray receiving end being in the form of a hub portion in which the collimator is mounted, which hub portion is journaled in an adapter member that is formed for securement to the specific Xray machine to which the positioning indicating device is to be applied. The journaling of the PID relative to the adapter member is such that the PID makes no movement axially thereof, relative to the adapter member, or the X-ray machine, on adjustment of same about the axis of the cone.

United States Patent [191 Stevenson [451 Feb. 4, 1975 POSITION INDICATING DEVICE FOR DENTAL X-RAY MACHINES 3,745,344 7/1973 Updegrave ..250/70 OTHER PUBLlCATlONS The Reduction of Unnecessary X-ray Exposure During lntraoral Examinations, by R. A. Goepp et al., from Oral Surgery. Oral Medicine and Oral Pathology, Vol. 16,No. 1, Jan., 1963, pages 39-45.

Primary ExaminerArchie R. Borchelt Assistant Examiner-B. C. Anderson Attorney, Agent, or Firm-Mann, Brown, McWilliams & Bradway [57] ABSTRACT A position indicating device for dental X-ray machines comprising a lead lined tubular member having an X-ray receiving end and an X-ray emitting end, with the tubular member at its X-ray receiving end being in the form of a hub portion in which the collimator is mounted, which hub portion is journaled in an adapter member that is formed for securement to the specific X-ray machine to which the positioning indicating device is to be applied. The journaling of the PID relative to the adapter member is such that the PID makes no movement axially thereof, relative to the adapter member, or the X-ray machine, on adjustment of same about the axis of the cone.

4 Claims, 3 Drawing Figures PATENTEDFEB "4191s 3.864.576

FIG-.2

POSITION INDICATING DEVICE FOR DENTAL X-RAY MACHINES This invention relates to a position indicating device for dental x-ray machines, and more particularly, to a collimating cone arrangement for use in dental radiography.

Dental x-ray machines conventionally are equipped with a position indicating device, (formerly commonly called a cone, or tube, and more recently called a position indicating device or PID) that is used to both limit the size of the useful x-ray beam employed in exposing the x-ray film located within the patients mouth, and to facilitate the alignment of the beam with the x-ray film. Commercially, such devices are constructed for removable application to the x-ray machine, and at the present time there are approximately 20 different ways to secure the cone to the machine, including variations of the familiar bayonet, snap-in and screw-in type mounting arrangements.

During use of the dental x-ray machine in the practice of dental radiography, it frequently is desirable to adjust the PID about its axis relative to the machine. This has to be done when the PID is of the rectangular type, to accommodate the position of the long dimension of the film within the patients mouth, due to the fact that it will vary depending on, for instance, whether posterior or anterior film holding instruments are being employed. Where the PID is threadedly mounted to provide this adjustment arrangement, the PID moves axially of the beam, thereby changing the distance between the x-ray generating device (the anode of the x ray tube) and the opening in the PID collimator, with consequent changing effect on the x-ray beam that emanates from the PID.

A principal object of the invention is to provide a position indicating device (PID) for dental x-ray machines in which the PID is arranged to permit 360 adjustment of same about its axis without varying the distance between the x-ray beam generating device and the beam restricting opening in the PID collimator.

Another object of the invention is to provide a position indicating device for dental x-ray machines in which the collimator is located within the PID but at the x-ray receiving end of same to minimize drift of the x-ray machine head.

Other objects of the invention are to provide a position indicating device for dental x-ray machines that permits full rotational adjustment of the PID, as desired, about its longitudinal axis, while accommodating the various types of PID mounting arrangements in commercial use, to provide a position indicating device for dental x-ray machines that is readily applicable to existing equipment, and to provide a position indicating device that is economical of manufacture, convenient to mount and use, and effective in operation.

In accordance with this invention, a position indicating device or cone for dental x-ray machines is provided comprising a lead lined tubular member having an x-ray receiving end and an x-ray emitting end, in which the tubular member at its x-ray receiving end is in the form of a hub portion in which the collimator is mounted, which hub portion is journaled in an adapter member that is specifically formed for securement to the specific x-ray machine to which the position indicating device is to be applied. The journaling of the PID relative to the adapter member is such that the PID makes no movement axially thereof, relative to the adapter member or the machine, on adjustment of same about the axis of the cone. On such adjustment movement, the adapter remains in its mounted position on the x-ray machine.

Other objects, uses and advantages will be obvious or become apparent from a consideration of the following detailed description and the application drawing:

IN THE DRAWING FIG. 1 is a longitudinal cross-sectional view through one embodiment of the invention, showing in dashed lines the x-ray beam collimated by the device on operation of the dental x-ray machine to which it is applied (not shown) to expose a dental film within the patients mouth;

FIG. 2 is a fragmental view ofthe mounted end of the position indicating device, but on an enlarged scale; and

FIG. 3 is an end view of the tubular member or component of the PID, taken substantially along line 33 of FIG. 2 but shown on a somewhat reduced scale.

However, it is to be distinctly understood that the specific drawing illustrations provided are supplied primarily to comply with the requirements of the Patent Laws, and that the invention may have other embodiments that will be obvious to those skilled in the art, and which are intended to be covered by the appended claims.

Reference numeral 10 generally indicates a preferred embodiment of the invention as arranged for application to a dental x-ray machine.

The position indicating device or cone 10 generally comprises a tubular member 12 that defines at its end 14 a round hub portion 16 that is counterbored as at 18 to receive collimating material 20 that conventionally is in the form of lead sheathing or the like. The collimating material 20 is formed to define an aperture 22 through which the x-rays emanating from the x-ray machine (not shown) to which the device 10 is attached pass into the tubular member 12 to form the x-ray beam 24.

As indicated in FIG. 3, the tubular member 12 defines a bore 25 that is of rectangular transverse crosssectional configuration, and accordingly the collimator aperture opening 22 is of corresponding rectangular transverse cross-sectional configuration, such that the x-ray beam 24 at the end 15 of the tubular member 12 substantially conforms to the rectangular crosssectional configuration of the tube 12 at its end 15.

The rectangular configuration of the tubular member 12 and its collimating opening 22 are arranged for use in connection with rectangular dental instrumentation. However, for purposes of this invention, the bore 25 of the tubular member 12, and the collimator aperture 22, may be circular in configuration for use in connection with circular instrumentation in accordance with standard practices.

The bore 25 of the tubular member 12 is lead lined, as indicated at 27, to a suitable thickness to confine scatter radiation in normal exposure. The end 15 of tubular member 12 is equipped with a suitable end cap 29 which may be suitably formed for cooperation with positioning frames of the dental instrumentation employed.

The collimating material 20 is held in place by a retainer ring or disc 26 which has a rim 29 that substantially conforms to the diameter of counterbore l8, and specifically the counterbore side wall 31. As indicated in FIG. 3, the ring 26 is staked in place against the material 20, as at 33. The side wall 31 of the counterbore 18 is formed with a protrusion or lug 28 that keys the collimating material 20 and retainer ring 26 against rotation relative to tubular member 12, with the rims of the collimating material and the ring 26 being suitably indented to receive the lug 28, as indicated in FIG. 3.

The hub portion 16 of tubular member 12 is formed to define a peripheral rib 30 formed on either side of same with bearing surfaces 32 and 34 against which are applied bearing rings 36 and 38 that are formed from a suitable antifriction material such as nylon or the product sold under the trademark Teflon by E. I. Du- Pont de Nemours and Co.

Operably associated with the tubular member 12 is an adapter member 40 of annular configuration defining a hub portion 42 including a radial flange 44 formed with a rim wall 46 which defines with the flange 44 a socket 48 that receives the tubular member hub portion 16 as well as bearing rings 36 and 38.

Cooperating with the adapter member rim wall 46 is a collar 50 that is formed with a radial flange 52 defining a bearing surface 54 adapted to engage the bearing ring 36. The collar 50 and adapter member rim wall 46 are threaded as indicated at 56 whereby the collar 50 may be turned on to the adapter member rim wall 46 to rotatably mount tubular member 12 on the adapter member 40 by clamping the tubular member peripheral rib between the bearing rings 36 and 38. Bearing ring 38 seats against bearing surface 58 defined by the adapter member radial flange 44.

The adapter member rim wall 46 and the collar 50 are formed with the respective openings 60 and 62 (see FIG. 2) that are adapted to be aligned to receive suitable shear pin 64 which holds the collar 50 against threaded movement relative to the adapter member rim wall 46 at the desired degree of compression on rings 36 and 38.

It is to be noted that the bearing ring 36 is proportioned such that it spaces the collar flange 52 from the adapter member rim wall 46, and the bearing member 38 is proportioned to space the adapter member flange 44 from the face 66 of the tubular member hub portion 16. The peripheral surface 68 of the tubular member rib 30 and rings 36 and 38 are proportioned so that surface 68 will be spaced from the adapter member rim wall 46, for free movement relative thereto. Thus, the tubular member 12, while having its peripheral rib 30 firmly gripped between the bearing rings 34 and 38, may be readily turned relative to the adapter member 40, by virtue of the antifriction characteristics of the bearing rings 36 and 38.

The hub portion 42 of the adapter member 40 is suitably shaped to accommodate one of the conventional mounting and locking recesses of conventional x-ray machines for dental work. Thus, the hub portion 42 may be lugged as indicated at 70 for providing a familiar form of bayonet type lock arrangement. Alternately, the hub portion 42 may be externally threaded for cooperation with internal threading ofthe x-ray machine that employs this type of PID connection. Similarly, the hub portion 42 may be equipped for providing one of the snap-in type PID mounting arrangements, or any of the other familiar types of PID mounting arrangements that are conventionally employed.

In other words, the adapter member 40, in accordance with this invention, is shaped and arranged to accommodate one of the many conventional ways of mounting PIDs on dental x-ray machines that are in use commercially.

In use, the device is applied to a conventional dental x-ray machine by securing the adapter member 40 in place on the machine head, with the adapter member 40 that is used being specifically adapted for mounting on the particular machine in question. The tubular member 12 is aimed at the target area to be x-rayed, it being preferred that the dentist employ film holding instrumentation of the type that is conventionally designed to facilitate such aiming. In this connection, where the rectangular positioning device illustrated is employed, rectangular instrumentation should be em ployed, and rotation of the tubular member 12 relative to the adapter member 40 is required as the dentist, for instance, changes his instruments for accommodating anterior and posterior positions (which requires a 90 rotation).

In accordance with this invention, the distance between the aperture 22 and the source 72 of the x-ray beam remains the same even though the tubular mem ber 12 may be rotated zero through 360 degrees or more relative to the adapter member 40. Note, also, that since the collimating material 20 is fixed with re spect to tubular member 12, the distance between the aperture 22 and the end 15 of the tubular member 12 remains fixed.

As important consideration in the present invention is that the relatively heavy collimating material 20 is located at the portion of the tubular member 12 which is closest to the x-ray machine head to which the device 10 is to be applied. This locates the center of gravity of the device 10 as close as reasonably possible to the x-ray machine head to which it is attached.

It is pointed out that the heads of dental x-ray machines are usually mounted on a linkage that is arranged for vertical and horizontal movement. The nature of this linkage is such that the further the center of gravity of the cone is positioned in front of the head, the greater the tendency ofthe head to drift forwardly, or in the direction of the patient, when released by the dentist after initial positioning. Having the collimating material 20 disposed within the socket 48 of the adapter member 40, with the adapter member hub portion being received within the head socket that is adapted to receive same, brings the center of gravity of the device 10 sufficiently close to the head to substantially eliminate the drifting problem.

Furthermore, the positioning of the collimating mate rial where shown in the drawings avoids having unwanted radiation within the tubular member itself, and confines radiation, except for the useful beam indi cated at 25, to the machine head. This avoids having to apply additional x-ray absorbative materials to the PID to take care of undesired radiation.

The tubular member 12 and adapter member 40 may be formed from aluminum or the like while the end cap 29 (which may be omitted) is formed from a suitable plastic. Where filtration is required, a disc formed from aluminum is seated in counterbore formed in the adapter member 40, with the aluminum disc being a solid disc of half value thickness as desirable or neces sary.

The foregoing description and the drawings are given merely to explain and illustrate the invention and the invention is not to be limited thereto, except insofar as the appended claims are so limited, since those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention:

I claim:

1. In a position indicating device for x-ray machines, wherein said device includes a tubular member that is rectilinear axially of same, with said member defining a bore of rectangular transverse cross-sectional configuration that extends the length of same and having its internal surfacing lined for x-ray absorption and defining an x-ray receiving end and an x-ray emitting end, and an adapter member for securing said tubular member to an x-ray machine and secured to said x-ray receiving end of said tubular member,

the improvement wherein:

said tubular member at said x-ray receiving end of same is formed to define a round hub portion having a peripheral rib integral therewith and thereabout defining annular bearing surfaces on either side of same that lie in parallel planes extending normally of said tubular member,

with one of said bearing surfaces facing in the direction of said tubular member x-ray emitting end and the other of said bearing surfaces facing in the direction of said tubular member x-ray receiving end,

said member hub portion being formed with a circular counterbore that faces oppositely of said x-ray emitting end of said member and lies at said x-ray receiving end thereof,

said counterbore defining a side wall that is in circumambient relation about said tubular member bore,

collimating material received in said counterbore and extending from said counterbore side wall across said tubular member bore and being formed to define an x-ray collimating opening centered within said tubular member bore and being of a shape complementing that of said tubular member emitting end,

said member hub portion being formed to define between said counterbore and said other bearing surface an annular face that forms the terminal end surface of said tubular member at said x-ray receiving end of same,

with an annular retaining disc being received in said counterbore about the portion of said collimating material adjacent said counterbore side wall,

means for fixing said retaining disc to said tubular member to secure said collimating material to said tubular member within said counterbore,

said disc extending short of said tubular member end surface axially of said tubular member and being separated from said adapter member,

said adapter member further comprising:

a hub portion including means for securing same to the x-ray machine in the mounted position of said device,

said adapter member hub portion defining a radial flange having a bearing surface and an axially extending rim wall defining a socket in which said tubular member hub portion is received with said peripheral rib being encompassed by said adapter member rim wall and said adapter member flange bearing surface opposing said rib other bearing surface,

a securing collar received over said adapter member rim wall and defining a radial flange directed radially inwardly of said collar and having a bearing surface that opposes said rib one bearing surface,

a first antifriction ring interposed between said one bearing surface of said rib and said collar flange bearing surface in face to face engagement therewith,

a second antifriction ring interposed between said rib other bearing surface and said adapter member flange bearing surface in face to face engagement therewith,

said collar and said adapter member rim wall having threaded engagement for clamping said rings against said tubular member rib under predetermined compression to journal said tubular member in said adapter member,

and means for keying said collar and adapter member rim wall together for maintaining said predetermined compression of said rings,

said first antifriction ring being proportioned axially of said tubular member to space said collar flange from said adapter member rim wall when said first ring is clamped between said rib one bearing surface and said collar flange bearing surface,

said second antifriction ring being proportioned axially of said tubular member to space said adapter member flange from said tubular member end surface when said second ring is clamped between said rib other bearing surface and said adapter member flange bearing surface,

said rib defining a peripheral surface that is spaced from said adapter member rim wall radially inwardly of said adapter member rim wall,

said collar flange defining a bore having an internal diameter proportioned to space said collar flange from said tubular member,

whereby, on rotation of said tubular member relative to said adapter member for adjustment of said tubular member relative to said adapter member, said collimating opening remains stationary axially of said adapter member for 360 degrees of such rotation, and said collar and said adapter member are free of engagement with said tubular member whereby said rotational movement of said tubular member relative to said adapter member is opposed by frictional forces only at said bearing surfaces.

2. The device set forth in claim 1 wherein:

said collimating material and said retaining disc are keyed to said tubular member hub portion against rotation with respect thereto about the axis thereof.

3. The device set forth in claim 1 wherein:

said antifriction rings are formed from a nonmetallic antifriction material.

4. The device set forth in claim 3 wherein:

said bearing surfaces are planar in configuration and extend normally of said axis of said tubular member,

said antifriction rings each defining planar end surfaces against which the respective bearing surfaces engage. 

1. In a position indicating device for x-ray machines, wherein said device includes a tubular member that is rectilinear axially of same, with said member defining a bore of rectangular transverse cross-sectional configuration that extends the length of same and having its internal surfacing lined for x-ray absorption and defining an x-ray receiving end and an x-ray emitting end, and an adapter member for securing said tubular member to an x-ray machine and secured to said x-ray receiving end of said tubular member, the improvement wherein: said tubular member at said x-ray receiving end of same is formed to define a round hub portion having a peripheral rib integral therewith and thereabout defining annular bearing surfaces on either side of same that lie in parallel planes extending normally of said tubular member, with one of said bearing surfaces facing in the direction of said tubular member x-ray emitting end and the other of said bearing surfaces facing in the direction of said tubular member x-ray receiving end, said member hub portion being formed with a circular counterbore that faces oppositely of said x-ray emitting end of said member and lies at said x-ray receiving end thereof, said counterbore defining a side wall that is in circumambient relation about said tubular member bore, collimating material received in said counterbore and extending from said counterbore side wall across said tubular member bore and being formed to define an x-ray collimating opening centered within said tubular member bore and being of a shape complementing that of said tubular member emitting end, said member hub portion being formed to define between said counterbore and said other bearing surface an annular face that forms the terminal end surface of said tubular member at said x-ray receiving end of same, with an annular retaining disc being received in said counterbore about the portion of said collimating material adjacent said counterbore side wall, means for fixing said retaining disc to said tubular member to secure said collimating material to said tubular member within said counterbore, said disc extending short of said tubular member end surface axially of said tubular member and being separated from said adapter member, said adapter member further comprising: a hub portion including means for securing same to the x-ray machine in the mounted position of said device, said adapter member hub portion defining a radial flange having a bearing surface and an axially extending rim wall defining a socket in which said tubular member hub portion is received with said peripheral rib being encompassed by said adapter member rim wall and said adapter member flange bearing surface opposing said rib other bearing surface, a securing collar received over said adapter member rim wall and defining a radial flange directed radially inwardly of said collar and having a bearing surface that opposes said rib one bearing surface, a first antifriction ring interposed between said one bearing surface of said rib and said collar flange bearing surface in face to face engagement therewith, a second antifriction ring interposed between said rib other bearing surface and said adapter member flange bearing surface in face to face engagement therewith, said collar and said adapter member rim wall having threaded engagement for clamping said rings against said tubular member rib under predetermined compression to journal said tubular member in said adapter member, and means for keying said collar and adapter member rim wall together for maintaining said predetermined compression of said rings, said first antifriction ring being proportioned axially of said tubular member to space said collar flange from said adapter member rim wall when said first ring is clamped between said rib one bearing surface and said collar flange bearing surface, said second antifriction ring being proportioned axially of said tubular member to space said adapter member flange from said tubular member end surface when said second ring is clamped between said rib other bearing surface and said adapter member flange bearing surface, said rib defining a peripheral surface that is spaced from said adapter member rim wall radially inwardly of said adapter member rim wall, said collar flange defining a bore having an internal diameter proportioned to space said collar flange from said tubular member, whereby, on rotation of said tubular member relative to said adapter member for adjustment of said tubular member relative to said adapter member, said collimating opening remains stationary axially of said adapter member for 360 degrees of such rotation, and said collar and said adapter member are free of engagement with said tubular member whereBy said rotational movement of said tubular member relative to said adapter member is opposed by frictional forces only at said bearing surfaces.
 2. The device set forth in claim 1 wherein: said collimating material and said retaining disc are keyed to said tubular member hub portion against rotation with respect thereto about the axis thereof.
 3. The device set forth in claim 1 wherein: said antifriction rings are formed from a nonmetallic antifriction material.
 4. The device set forth in claim 3 wherein: said bearing surfaces are planar in configuration and extend normally of said axis of said tubular member, said antifriction rings each defining planar end surfaces against which the respective bearing surfaces engage. 